/**
 * 直接返回fulfilled状态的Promise对象
 */
const test = () => {
  const a = Promise.resolve(1);
  console.log('a end');
  const b = a.then(ret => {
    console.log('a then ret', ret);
  });
  const bb = b;
  console.log('b end');
};
test();
console.log('all end');

